Impact of water/PDMS phase ratio, volume of PDMS, and sampling time on Stir Bar Sorptive Extraction (SBSE) recovery of some pesticides with different K_O/W

Abstract

In Stir Bar Sorptive Extraction (SBSE) organic analytes are enriched from aqueous samples by sorption onto a thick film of polydimethylsiloxane (PDMS) coated on a glass‐enveloped magnet. Sampled analytes are recovered by thermodesorption (TDS) and analysed on‐line by cGC‐MS. This study evaluates the SBSE recovery as a function of KO/W, the phase ratio (β), PDMS volume (20, 40, and 110 μL), sample volumes (4, 10, 100, and 1000 mL), and sampling time (0.67, 1, 2, 4, 5, 6, and 24 h) for three pesticides with different KO/W [parathion methyl (KO/W: 7.24×102), β‐endosulfan (KO/W: 6.8×103), and buprofezin (KO/W: 2.0×104)]. Experimental recoveries with SBSE in reasonable sampling times were found to be mainly conditioned by β, which must be as low as possible either by operating on small sample volumes or by using stir bars coated with high PDMS volume when samples of relatively large volume are analysed.

Polydimethylsiloxane Rods for the Passive Sampling of Pesticides in Surface Waters

“…Several studies have correlated the partitioning coefficient of analytes K sw with their octanol-water distribution coefficient (K ow ) [13,[20][21][22][23][24].…”

“…With the assumption that K sw is correlated to the octanol-water distribution coefficient K ow , the extraction recovery on PDMS, in general, increases with increasing hydrophobicity. Moreover, the phase ratio β can also affect the extraction recovery [24]. Figure 1 shows the extraction recovery of the target pesticides sorted by increasing hydrophobicity for the four types of synthesized PDMS rods and for Twisters.…”

Sample Preparation for Trace Analysis by Chromatographic Methods

“…[171] The advantage of SBSE is a higher enrichment factor combined with the application range and extraction mechanism of SPME. [172] Transfer of the analyte from the bar is achieved either by GC thermal desorption, or by elution with an LC solvent. As with SPME, the stir bar can also be used to sample the volatiles and semi-volatiles in the headspace above the sample.…”

Extração sortiva em barra de agitação para análise de fármacos em fluidos biológicos

“…Embora, não seja totalmente correto, o coeficiente de distribuição octanol/água de um analito específico nos dá um bom indicativo da eficiência da extração SBSE, quando utilizada a fase extratora PDMS. [12][13][14]16 O equilíbrio de sorção é dependente da razão entre as fases, sendo diretamente dependente da quantidade de PDMS da fase extratora. Esta relação é ilustrada na Equação 1.…”